Various methods for extracorporeal blood treatment are known. In the case of hemodialysis (HD), the blood of the patient is cleaned in an extracorporeal blood circuit which comprises a dialyzer. The dialyzer has a blood chamber and a dialysis fluid chamber which are separated by a semipermeable membrane.
Whereas the dialysis fluid flows through the dialysis fluid chamber during hemodialysis (HD), with certain substances being transported through the membrane on account of the diffusion between the dialysis fluid and the blood, the dialysis fluid does not flow through the dialysis fluid chamber of the dialyzer during hemofiltration (HF). In hemofiltration (HF), certain substances are effectively removed through the membrane of the filter due to convection. Hemodiafiltration (HDF) is a combination of the two methods.
It is widely known to replace part of the fluid, taken from the patient via the membrane of the dialyzer or the filter, by a sterile substitution fluid which is supplied to the extracorporeal blood circuit either upstream or downstream of the dialyzer. Apparatuses for extracorporeal blood treatment are known, in which apparatuses the dialysis fluid is produced online from fresh water and concentrates and the substitution fluid is produced online from dialysis fluid.
Different tubular line systems, which are designed for single use and are inserted into the blood treatment apparatus, are used for the various extracorporeal blood treatments. By way of example, tubular lines of tubular line systems whose internal diameters differ from one another are known for treating adults or children.
The extracorporeal blood treatment apparatuses comprise a number of pumps by means of which the blood of the patient, the substitution fluid or rinsing fluids are pumped through the tubular lines of the tubular line systems.
Peristaltic pumps are used to pump fluids in the extracorporeal blood treatment apparatuses, in which at least one constriction or occlusion site moves along the elastic tube serving as pump space. In the most commonly used design of peristaltic tube pumps, the elastic tube is completely closed off at the constriction or occlusion site. It is for this reason that these pumps are also known as occluding tube pumps. The most commonly used occluding tube pump is a roller pump, into which a section of the tubular line of the tubular line system is inserted.